The ability to detect specific nucleic acid sequences in a sample has resulted in new approaches in diagnostic and predictive medicine, environmental, food and agricultural monitoring, molecular biology research, and many other fields. In addition, new sequencing methodologies provide the means for rapid high-throughput nucleic acid sequencing.
Additional methods, especially methods that facilitate analysis of many targets and/or the analysis of many samples simultaneously across a broad range of concentrations in a sample would be of great benefit.
Microfluidic devices can be used for analytical, preparative, metering, and other manipulative functions on a scale not imagined until recently. The advantages of microfluidic devices include conservation of precious reagents and samples, high density and throughput of sample analysis or synthesis, fluidic precision and accuracy at a level scarcely visible to the unaided eye, and a space reduction accompanying the replacement of counterpart equipment operating at the macrofluidic scale. Associated with the reduction in size and the increased density of microfluidic devices is increased complexity and higher engineering and fabrication costs associated with increasingly intricate device architecture.
Recently, there have been concerted efforts to develop and manufacture microfluidic systems to perform various chemical and biochemical analyses and syntheses. Additionally, microfluidic devices have the potential to be adapted for use with automated systems, thereby providing the additional benefits of further cost reductions and decreased operator errors because of the reduction in human involvement. Microfluidic devices have been proposed for use in a variety of applications, including, for instance, capillary electrophoresis, gas chromatography, and cell separations.
However, realization of these benefits has often been thwarted because of various complications associated with the microfluidic devices that have thus far been manufactured. For instance, many of the current microfluidic devices are manufactured from silica-based substrates, which are difficult and complicated to machine. As a result, many devices made from such materials are fragile. Furthermore, transport of fluid through many existing microfluidic devices requires regulation of complicated electrical fields to transport fluids in a controlled fashion through the device.
Thus, in view of the foregoing benefits that can be achieved with microfluidic devices but the current limitations of existing devices, there remains a need for microfluidic devices designed for use in conducting a variety of chemical and biochemical analyses. Because of its importance in modern biochemistry, there is a particular need for devices that can be utilized to conduct a variety of nucleic acid amplification reactions, while having sufficient versatility for use in other types of analyses as well.
Devices with the ability to conduct nucleic acid amplifications would have diverse utilities. For example, such devices could be used as an analytical tool to determine whether a particular target nucleic acid of interest is present or absent in a sample. Thus, the devices could be utilized to test for the presence of particular pathogens (e.g., viruses, bacteria, or fungi), and for identification purposes (e.g., paternity and forensic applications). Such devices could also be utilized to detect or characterize specific nucleic acids previously correlated with particular diseases or genetic disorders. When used as analytical tools, the devices could also be utilized to conduct genotyping analyses and gene expression analyses (e.g., differential gene expression studies). Alternatively, the devices can be used in a preparative fashion to amplify sufficient nucleic acid for further analysis such as sequencing of amplified product, cell-typing, DNA fingerprinting, and the like. Amplified products can also be used in various genetic engineering applications, such as insertion into a vector that can then be used to transform cells for the production of a desired protein product.
Despite these advances in microfluidic design and use, it would be useful to reduce the complexity of microfluidic chips and simplify their operation. Additionally, a need exists for an increased ability to recover reaction products from microfluidic devices. Thus, there is a need in the art for improved methods and systems related to microfluidic devices.